Control apparatus for refrigeration system



April 4, 1967 l. BERGER ET AL 3,312,081

CONTROL APPARATUS FOR REFRIGERATION SYSTEM Filed Aug. 5, 1965 INVENTORS. ISAAC BERGER. MMK F. SCHMIDT.

ATTORNEY.

United States Patent 3,312,081 CONTROL APPARATUS FOR REFRIGERATION SYSTEM Isaac Berger and Jack F. Schmidt, De Witt, N.Y., assignors to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Aug. 3, 1965, Ser. No. 476,858 Claims. (Cl. 62158) This invention relates to a refrigeration system, and more particularly, to a control arrangement for the compressor of the refrigeration system.

Refrigeration systems usually incorporate one or more protective devices, each effective at a certain malfunction in the system or the system compressor to render the compressor inoperative. Typical protective devices are, for example, an over-temperature sensor for the compressor motor windings, system pressure measuring devices, devices for sensing adequate compressor 'oil pressure, etc. On stoppage of the system compressor, whether as a result of a malfunction or, more commonly, the satisfaction of demand on the system, it is desirable that immediate restarting of the compressor be precluded.

In refrigeration systems which incorporate a control to prevent immediate restarting of the system compressor or compressors after stoppage thereof, where the compressor stoppage is due to a prevailing system or compressor malfunction, the compressor or compressors are nevertheless restarted, subject to the control imposed delay, indefinitely until the operator becomes cognizant of the system malfunction or the compressor becomes totally inoperative. This situation is of particular concern in commercial systems Where the system is apt to be left unattended for prolonged periods of time.

It is a principal object of the present invention to provide a new and improved control arrangement for compressors.

It is a further object of the present invention to provide a control arrangement elfective to limit the number of compressor restarts that may be made within a predetermined period of time.

It is an object of the present invention to provide, in conjunction with a control for delaying restart of a compressor for a timed interval subsequent to each deenergization thereof, an apparatus effective to render the restarting control inoperative following a predetermined number of compressor restarts.

It is an object of the present invention to provide an apparatus which counts each deenergization of a refrigeration system compressor effective following a preset number of compressor deenergizations to prevent further operation of the compressor.

It is a further object of the present invention to provide an apparatus for limiting the number of compressor restarts having means for automatically resetting the apparatus upon successful operation of the compresor.

The invention relates to a refrigeration system comprising in combination, a compressor; an energizing circuit for the compressor; condition sensing means operable at the occurrence of the predetermined malfunction to interrupt the compressor energizing circuit and stop the compresor; timer controlled means eifective to prevent completion of the compresor energizing circuit and startup of the compressor for a timed interval following each stopping thereof; a step switch effective when moved through a predetermined series of steps to interrupt the compressor energizing circuit and prevent start-up of the compresor; and means for moving the step switch one step at each stop-start cycle of the compressor, whereby when the number of compressor cycles equals the predetermined series of steps through which the step switch 3,312,081 Patented Apr. 4, 1967 moves, the step switch prevents start-up of the compressor.

Other objects and advantages will be apparent from the ensuing description and the accompanying drawings, in which:

FIGURE 1 is a schematic representation of a refrigeration system incorporating the compressor control arrangement of the present invention.

FIGURE 2 is a wiring diagram of the compressor control arrangement of the present invention, and

FIGURE 3 is a block diagram illustrating the position of the several control switches during an operating time cycle.

Referring to FIGURE 1 of the drawings, there is shown a refrigeration system incorporating the control arrangement of this invention. The system includes an outdoor heat exchange coil or condenser 2 connected by means of line 3 with the discharge side of a suitable refrigerant compression mechanism, for example, a reciprocating type compressor 4. The gaseous refrigerant from compressor 4 flowing through outdoor coil 2 is condensed by ambient air from outdoor fan 5. Liquid refrigerant from coil 2 flows through line 6, thermal expansion valve 8, and line 9 to indoor coil or evaporator 10. It is understood that other suitable expansion devices, i.e. capillary tube may be employed in place of expansion valve 8.

Liquid refrigerant in indoor coil 10 is vaporized by the stream of air from indoor fan 12, the cooled air being thereafter passed to the area being conditioned by suitable means (not shown). Vaporous refrigerant from coil 10 flows through line 13 to compressor 4. Control valve 15 is provided in refrigerant line 6. Valve 15 includes a suitable solenoid operator 15' therefor. Solenoid operator 15', when energized, opens valve 15.

Referring to FIGURE 2 of the drawings, the energizing windings of compressor drive motor 16 are connected through contacts 19, 20, across leads L L L Contacts 19, 20 are closed in sequence as will be more apparent hereinafter to effectuate part winding start-up of compressor drive motor 16. Leads L L L, are connected to a suitable source of alternating current power (not shown). It is understood that a two phase source of electrical power may be employed if the circuit is suitably modified.

Outdoor and indoor fan motors 22, 23, respectively, are connected by switches 41, 25 across leads L L A control relay 26 is series connected with temperature responsive switch 27 across leads L L Switch 27 responds to temperature conditions of the area being cooled.

Compressor 4 preferably includes a suitable crankcase heater, such as resistance 29. Heater 29 is series connected with switch 30 across leads L L Timer switch contact 32' is in series with resistance heater 29.

Timer 35 is series connected with timer switch 32, step switch 36, winding temperature responsive switch 37, dis charge line thermostat switch 38, system high pressure switch 39, system low pressure switch 40,. and switch 41 across leads L L Timer switch 32 when moved into engagement with contact 32, series connects timer 35 with switch 30 across leads L L Switches 37, 38, 39, 40 and oil pressure responsive switch 44, protect the refrigeration system, and compressor 4 in particular, against various malfunctions. As will be more apparent hereinafter each of switches 37, 38, 39, 4t) and 44 deenergize compressor 4 at the occurrence of a specific fault.

Temperature responsive switch 37 is disposed in intimate heat exchange relation with the windings of the compressor motor 16. Switch 37 opens at the occurrence of a potentially damaging motor winding temperature. Switch38, arranged in heat exchange relation with disrefrigerant under pressure.

charge line 3, opens at a predetermined high refrigerant discharge temperature.

Switches 39, 4d are arranged to sense refrigerant pressure conditions in discharge and suction lines 3, 13, respectively. Switch 39 deenergizes the compressor at a predetermined high refrigerant pressure in line 3 while switch 40 deenergizes the compressor at a predetermined low refrigerant pressure in line 13. Switch 41] includes a second switch contact 40 in the reset relay circuit. It is understood that the refrigeration system is charged with At start-up, normal system pressure closes switches 40, 40 prior to the operation of compressor 4.

Switch 44, which senses compressor oil pressure conditions, opens when compressor oil pressure conditions are below a selected pressure to interrupt the energizing circuit to the compressor 4. To enable compressor 4 to start, 'tirner'switch 45 is provided to bypass switch 44 for a predetermined time at compressor start-up, as will be more 'fully explained hereinafter.

Oil pressure responsive switch 44, switch 46 and starting relay 48 are series connected with step switch 36, switches 37, 38, 39, 40 and switch 41 across leads L L Starting relay 48, when energized, closes contacts 19 to energize a part of the compressor motor windings. Relay 49 is connected in parallel wit-h starting relay 48 through timer switch 51. Relay 49, when energized, closes contacts 21 to energize the remainder of the compressor drive motor windings. Timer 35 moves timer switch 51 to close contact 51 and interrupt the energizing circuit to relay 49 at compressor start-up, as will be more apparent hereinafter.

A holding relay 53 is connected across timer switch 51 and relay 49. Holding relay 53, when energized, opens switch 30 while closing switches 41, 46 and 55, respectively. Resistor 57 and diode 58 are series connected with holding relay 53. Capacitor 59 is connected across holding relay 53. Diode 58 serves to limit current flow in the holding relay circuit to a single direction, and charge capacitor 59. As will be evident hereinafter, capacitor 59 serves to maintain holding relay 53 energized during the momentary interruption of the energizing circuit to holding relay 53 occurring during resetting of step switch 36.

Reset relay 62 is series connected by timer switch 63 with oil pressure responsive switch 44, step switch 36, switches 37, 38, 39, 40 and switch 41 across leads L L Timer switch 63, when moved to engage contact 63', series connects resetrelay 62 with step switch 65, reset switch 66, low pressure contact 40', switch 55 and switch 41 across leads L L Reset relay 62 is operably connected to switch arms 36', 65' of step switches 36, 65, respectively. When deenergized, relay 62 moves switch arms 36, 65' clockwise through one step or position. Arms 36', 65 of switches 36, 65 hold switches 36, 65 closed through a series of steps. In the exemplary showing, arms 36', 65 of switches each move through five steps to an open position. Switch arm 65 of switch 65 lags one step behind arm 36' of switch 36. For example, when switch arm 36' is at step #1, switch 65 is open. When switch 36 is open, switch 65 is at step #5.

Control relay switch 70 parallels switch 41. Solenoid 15 is series connected with control relay switch 72 across leads L L Timer 35 moves timer switches 32, 45, 51 and 63 in accordance with a preset time cycle. FIGURE 3 of the drawings illustrates an exemplary time cycle.

With the several switches of the control circuit diagram in the position shown in FIGURES 2 and 3 of the drawings, the refrigeration system is ready to start on a demand for cooling. This condition is represented by time on the time-cycle chart of FIGURE 3. On a demand for cooling of the area being conditioned, switch 27 closes I to energize control relay 26. Relay 26 closes control reenergizing circuit to the outdoor fan motor 22. Switch 25 completes an energizing circuit to the indoor fan motor 23. Switch 72 completes an energizing circuit to solenoid 15 to open valve 15.

Closure of switch 71) completes a circuit from lead L through switch 70, switches 37, 38, 39 and 40, step switch 36 and timer switch 32 to lead L to energize timer 35. At time A, timer 35 closes timer switch 45 to complete the bypass circuit for oil pressure switch 44. It is understood that since compressor 4 is deenergized, switch 44 is open. Timer 35 holds switch 45 closed until time D.

Following closure of switch 45, timer 35, at time B moves timer switch 51 to close contact 51 to complete energizing circuits to starting relay 48 and holding relay 53. Starting relay 48 closes contacts 19 to complete the energizing circuit to a part of the compressor motor windings. Holding relay 53 opens switch 30, interrupting the circuit to crankcase heater 29, and closes switches 41, 46 and 55. Closure of switch 41 bypasses control relay switch 7 0.

At the expiration of a relatively short time, at time C timer 35 moves timer switch 51 to open contact 51 and close contact 51" to complete a circuit from lead L through switch 41, switches 37, 38, 39' and 40, step switch 36, timer switch 45, switch 46 and timer switch 51 to lead L to energize relay 49. Relay 49 closes contacts 20 to energize the remainder of the compressor motor windings.

Reset relay 62 is energized through timer switch 63, oil pressure switch 44 or timer switch 45, step switch 36, switches 37, 38, 39 and 4t and switch 41. At the expiration of a relatively long interval, at time E, timer 35 moves timer switch 63 to open contact 63 and close contact 63'. Closure of contact 63 by timer switch 63 places reset coil 62 in series with step switch 65, reset relay switch 66, system low pressure switch 40', and switches 55, 41.

Shortly thereafter, at time F, timer 35 moves timer switch 32 to close contact 32' and connect timer 35 in series with switch 30. Since switch 31? is open due to the energization of coil 53 timer motor 35 is deenergized.

Upon satisfaction of the cooling demand, switch 27 opens to interrupt the energizing circuit to control relay 26 thereby opening switches 25, 70, 72. Switches 41, 25, when opened, interrupt the energizing circuits to outdoor and indoor fan motors 22, 23. Switch 72, when opened, interrupts the energizing circuit to solenoid 15 whereupon valve 15 is closed to interrupt the refrigerant line 6.

Since the refrigerant circuit is interrupted by closure of valve 15, pressures in compressor suction line 13 decrease. At a predetermined low suction pressure, switches 40, 40 open. Opening of switch 40 interrupts the energizing circuit to relays 48, 4 9, to open switches 19, 20, respectively, and deenergize the compressure motor windings. Holding relay 53 is deenergized closing switch 30. Closure of switch 30 completes an energizing circuit to the compressor crankcase heater 29, and, through timer switch '32, to timer 35. At time G, timer 35 moves switch 63 to close contact 63". Following the expiration of a relatively long interval, at time H timer 35 moves switch 32 to open contact 32' and close contact 32". Timer 35 is accordingly deenergized. The time cycle is completed.

With compressor 4 energized in response to a cooling demand, opening of any one of the switches 37, 38, 39, 40 or 44 in response to a malfunction interrupts the energizing circuits to relays 48, 49 to deenergize compressor motor 16 in the manner explained heretofore. Relay 53 is deenergized closing switch 30 and opening switches 41, 46, 55. Closure of switch 30 energizes the compressor crankcase heater 29 and, by means of timer switch 32, timer 35. Additionally, reset relay 62 is deenergized.

Deenergization of relay '62 moves step switch arms '36,

65' to the positions numbers 2 and 1 respectively. Step switch 65 is now closed.

At the expiration of the time F to H timer 35 moves switch 32 to open contact 32' and close contact 32". Timer 35 is energized through switch 32, step switch 36, switches 37, 38, 39, 40 and relay switch 70. The timer based control system energizes, in the timed cycle described heretofore, starting relay 48, holding relay 53, and relay 49 to restart the compressor drive motor 16.

It may be understood that should one of the switches 37, 38, 39, 40 open and reclose during the interval where timer switch 51 closes contact 51, on reclosure of the affected switch 37, 38, 39 or 40, the starting cycle is immediately resumed without imposition of the usual timed restarting delay. To minimize this possibility, the time interval B to C during which timer switch 51 closes contact 51 is extremely short, for example 2-3 seconds.

On a reoccurrence of the malfunction prior to opening of contact 63" and closure of contact 63' by timer switch 63, the switch 37, 38, 39, 40 or 44 responding to the malfunction opens to interrupt the energizing circuits to relays 48, 49, 53 and 62, again deenergizing the compressor motor as described above. Reset relay 62, when deenergized, moves step switch arms 36', 65 to positions numbers 3 and 2 respectively. Switch 46, opened upon deenergization of relay 53, interrupts the circuit to relays 48, 49 and 53. Following expiration of the timed interval, at time H, timer 35 moves switch 32 to open contact 32' and close contact 32". The compressor drive motor 16 is restarted as explained heretofore.

If the malfunction persists, the control attempts, following the expiration of each timed interval, to restart the compressor until reset coil 62 moves arm 36' of step switch 36 to the open or number 6 position. With step switch 36 open, the circuit to timer 35 through switch 32 is interrupted and further restarting of the compressor drive motor 16 by the control mechanism is precluded until closure or resetting of step switch 36. Step switch 36 is preferably of the type necessitating manual resetting thereof.

If, following the first restarting of the compressor drive motor by the control mechanism, the malfunction does not reoccur, at time B, timer switch 63 closes contact 63 while opening contact 63". Arm 36 of step switch 36 is then in the number 2 position while arm 65' of switch 65 is in the number 1 position. Upon closure of contact 63' reset relay 62 is connected series with step switch 65, reset relay switch 66, low pressure switch 40 and switches 55, 41. Switches 65, 40', 55 and 41 are closed. The circuit to reset relay 62 is accordingly interrupted and relay 62 deenergized whereby step switch arms 36, 65' are moved to ositions numbers 3 and 2 respectively.

On deenergization of reset relay 62, switch 66 closes. Closure of switch 66 completes the energizing circuit to relay 62 which opens switch 66 which, in turn, deenergizes relay 62. At each deenergization there-of, relay 62 moves step switch arms 36, 65 through one position. The intermittent energization and deenergization of reset relay 62 with corresponding movement of switch arms '36, 65' continues until step switch arms 65' reaches the open or number 6 position.

At the conclusion of the resetting process, arm 36' of step switch 36 is reset to the first or number 1 position. During the resetting process step switch 36 is momentarily opened. However, the resetting movement is so rapid and the interruption of the energizing circuits to relays 48, 49 so short that relays 48, 49 are not deenergized. The interruption of the energizing circuit to holding relay 53 during the resetting process discharges capacitor 59 through relay 53 to sustain energization of the relay 53. Switches 41, 46, 55 remain closed.

If compressor oil pressures do not reach that required to close switch 44 following compressor start-up, timer switch 45 interrupts the energizing circuits to starting and running relays 48, 49, holding relay 53, and reset relay 62 to terminate operation of the system as described heretofore. In this circumstance the control arrangement restarts the compressor following the predetermined timed interval as described above.

If desired, timer switch 32 may be placed in series with oil pressure responsive switch 44. In this arrangement the energizing circuit for timer motor 35 is from lead L to switch 70, switches 37, 38, 39, 40, step switch 36, timer switch 45 or switch 44 and timer switch 32 to lead L In the event that oil pressure 44 fails to close within the time prior to the opening of timer switch 45, the energizing circuits to coils 48, 49, 53, 62 are interrupted as well as the energizing circuit totimer motor 35. No further operation of the control arrangement is possible until timer switch 45 is closed as by manual resetting.

While we have described and illustrated a preferred embodiment of our invention, it will be understood that our invention is not limited thereto since it may be other- 'wise embodied within the scope of the following claims.

We claim:

1. In a refrigeration system having a compressor, the combination of a circuit for energizing said compressor; condition sensing means operable at the occurrence of a predetermined malfunction to interrupt said compressor energizing circuit and stop said compressor; timer controlled means etfective to prevent completion of said compressor energizing circuit and start-up of said compressor for a timed interval following each stopping thereof; a step switch effective when moved through a predetermined series of steps to interrupt said compressor energizing circuit and prevent start-up of said compressor; and means for moving said step switch one step at each stopstart cycle of said compressor whereby when the number of compressor cycles equals the predetermined series of steps through which said step switch moves, said step switch prevents start-up of said compressor.

2. The refrigeration system according to claim 1 including a control relay adapted when deenergized to interrupt said compressor energizing circuit; a circuit for energizing said control relay; means for resetting said step switch to a first of said predetermined series of steps upon successful ope-ration of said compressor, said step switch, when reset by said resetting means momentarily interrupting said control relay circuit; and means for temporarily energizing said control relay during interruption of said control relay circuit.

3. The refrigeration system according to claim 2 in which said means for temporarily energizing said control relay includes capacitance means connected across said control relay operative upon interruption of said control relay circuit to discharge through said control relay and maintain said control relay energized, and diode means in said control relay circuit effective to limit current flow through said control relay circuit to a single direction whereby on completion of said control relay circuit, said capacitance means is charged.

4. The refrigeration system according to claim 2 in Which said fault sensing means includes compressor oil pressure responsive means effective at the occurrence of a predetermined compressor oil pressure condition to interrupt said control relay energizing circuit and deenergize said compressor, said timer controlled means being arranged to render said compessor oil pressure responsive means ineffective for a predetermined time interval at compressor start-up.

5. The refrigeration system according to claim 2 in which said step switch moving means including a drive relay for said step switch adapted when deenergized to move said step switch one step, a first circuit for energizing said drive relay, and means responsive to interruption of said compressor energizing circuit to interrupt said first drive relay circuit.

6. The refrigeration system according to claim 5 in which said resetting means includes a second circuit for energizing said drive relay, said timer controlled means being adapted following energization of said compressor for a timed interval to complete said second drive relay circuit while interrupting said first drive relay circuit, and a control switch for said second drive relay circuit eifective when moved to interrupt said second-drive relay circuit, said control switch being drivingly connected to said drive relay whereby upon energization of said drive relay, said drive relay moves'said control switch to interrupt said second drive relay circuit.

7. The refrigeration system according to claim 6 in which said resetting means includes a second step switch in said second drive relay circuit eifective following movement through said predetermined series of steps to interrupt said second drive relay circuit, said second step switch being movable in unison with said first mentioned step switch and arranged to interrupt said second drive relay circuit when said first step switch is reset to the first of said predetermined series of steps to terminate operation of said resetting means.

8. In a refrigeration system having a compressor, the combination of a first circuit for energizing said compr-essor, a first switch adapted to a predetermined system fault to interrupt said first circuit, a second switch in said first circuit, timing means adapted to close said second switch at the expiration of a predetermined timed interval following interruption of said first circuit, joint closure of said first and second switches completing said first circuit to energize said compressor; a third switch adapted when moved through a series of positions to interrupt said first circuit and prevent re-energization of said compres- 8 sor; drive means for said third switch eifective at each interruption of said 'first circuit to move said third switch one position; and reset means adapted following a predetermined energization of said compressor to cause said .drive means to returnsaid third switch to a first of said series of positions.

9. The refrigeration system according to claim 8 in which said reset means causes said third switch to interrupt said first circuit; and means for temporarily maintaining said first circuit completed and said compressor energized upon movement of said third switch to said, first position by said reset means.

10. The refrigeration system according to claim 9 including an energizing circuit for said drive means, a fourth switch adapted upon predetermined movement to interrupt said drive means energizing circuit, said fourth switch being movable in unison with said third switch and arranged to interrupt said drivemeansenergizing circuit when said third switch is in said first position whereby said drive means is deenergized at the termination of the resetting cycle.

References Cited by the Examiner UNITED STATES PATENTS 2,836,769 5/1958 Sandin 3l722 3,053,057 10/1962 McGrath 62-228 X 3,178,615 4/1965 Miller 3l722 -MEYER PERLIN, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3, 312, 081 April 4 1967 Isaac Berger et a1.

It is hereby'certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5', line 48, after 0 insert Switch 66, under thecontrol of reset relay 6 2, is open. column 5, line 59, for "arms" read arm column 6, line 9, after "pressure" insert switch Signed andsealed this 26th day of December 1967.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer 

1. IN A REFRIGERATION SYSTEM HAVING A COMPRESSOR, THE COMBINATION OF A CIRCUIT FOR ENERGIZING SAID COMPRESSOR; CONDITION SENSING MEANS OPERABLE AT THE OCCURRENCE OF A PREDETERMINED MALFUNCTION TO INTERRUPT SAID COMPRESSOR ENERGIZING CIRCUIT AND STOP SAID COMPRESSOR; TIMER CONTROLLED MEANS EFFECTIVE TO PREVENT COMPLETION OF SAID COMPRESSOR ENERGIZING CIRCUIT AND START-UP OF SAID COMPRESSOR FOR A TIMED INTERVAL FOLLOWING EACH STOPPING THEREOF; A STEP SWITCH EFFETIVE WHEN MOVED THROUGH A PREDETERMINED SERIES OF THE STEPS TO INTERRUPT SAID COMPRESSOR ENERGIZING CIRCUIT AND PREVENT START-UP OF SAID COMPRESSOR; AND MEANS FOR MOVING SAID STEP SWITCH ONE STEP AT EACH STOPSTART CYCLE OF SAID COMPRESSOR WHEREBY WHEN THE NUMBER OF COMPRESSOR CYCLES EQUALS THE PREDETERMINED SERIES OF STEPS THROUGH WHICH SAID STEP SWITCH MOVES, SAID STEP SWITCH PREVENTS START-UP OF SAID COMPRESSOR. 